tbuckley/cabot-search huggingface dataset:
Abstract P1068: BubR1 Is A Novel Regulator Of Cardiac Development And Conduction
Authors: Renju Pun, Katelyn Jindra, Bryant Noss, Michael Kim, Brian North
Journal: Circulation Research (2022)

BubR1 (Budding uninhibited by Benzimidazole Related -1) is a kinase with a well-established role in regulating the spindle assembly checkpoint during mitosis. Recent studies have found that BubR1 insufficiency leads to premature aging phenotypes, and that BubR1 protein levels naturally decline with age, suggesting a role for BubR1 in aging and age-related diseases. Interestingly, mice carrying hypomorphic alleles of BubR1 expressing approximately 10% of the protein (BubR1 hypomorphic mice, BubR1 H/H ) die suddenly in a manner reminiscent of sudden cardiac death. Subsequent studies further demonstrated that BubR1 hypomorphic mice suffer from conduction abnormalities such as a prolonged QT interval. This abnormality can cause irregular rhythm in the ventricles that can lead to ventricular fibrillation and sudden cardiac death. However, the molecular and cellular basis linking these phenotypes to deficiency of BubR1 remain unknown. To define a role for BubR1 in the heart, we have taken a cellular and organismal approach to test the hypothesis that BubR1 regulates cardiac conduction. Utilizing a conditional BubR1 knockout mouse model, we have crossed this mouse to a cardiac-specific cre driver ( Nkx2.5-cre ) to assess the consequence of loss of BubR1 specifically in the heart. We observed that homozygous cardiac-specific deletion of BubR1 is embryonic lethal, indicating a critical role for BubR1 in heart development. Interestingly, electrocardiography (ECG) analysis of heterozygous deletion of BubR1 (55.4 ms ±3.3) also led to a prolonged QT interval in vivo as compared to wild type control (46.4 ms ±2.3) (N=10, p &lt; 0.01). To determine the molecular basis for our observed phenotypes in vivo, we have performed gene expression profiling on RNA isolated from hearts of 6-month-old BubR1 H/H and wild-type mice in which genetic pathways relating to cardiac conduction such as ion channels were altered in expression (N=3). Finally, we have also identified that intercellular communication is dysregulated upon depletion of BubR1. Together these studies suggests a novel mechanism by which loss of BubR1 may lead to adverse consequences for the heart in vivo .
Markov blankets and the preformationist assumption
Authors: Mads Dengsø, Ian Robertson, Axel Constant
Journal: Behavioral and Brain Sciences (2022)

Abstract Bruineberg and colleagues argue that a realist interpretation of Markov blankets inadvertently relies upon unfounded assumptions. However, insofar as their diagnosis is accurate, their prescribed instrumentalism may ultimately prove insufficient as a complete remedy. Drawing upon a process-based perspective on living systems, we suggest a potential way to avoid some of the assumptions behind problems described by Bruineberg and colleagues.
Abstract P2096: Long Qt Syndrome Type 3 Phenotype Dependence On Extracellular Sodium And The Perinexus In A Genetic Mouse Model
Authors: Xiaobo Wu, Gregory Hoeker, Robert G Gourdie, Seth Weinberg, Steven Poelzing
Journal: Circulation Research (2022)

Background: Long QT Syndrome Type 3 (LQT3) is caused by cardiac voltage-gated sodium channel (Nav1.5) gain of function and characterized by action potential duration (APD) prolongation. A guinea pig model of drug-induced LQT3 demonstrated that elevating sodium and widening the perinexus, an intercalated disc cleft adjacent to gap junctions, individually and synergistically exacerbate APD prolongation. The synergistic effect suggests that high sodium with cardiac edema is a risk factor for LQT3 patients. However, it remains unclear if this synergistic effect occurs in a genetic model of LQT3. Purpose: To investigate individual and combined effects of sodium concentration and perinexal widening in a genetic mouse model of LQT3. Methods: Ventricular action potential duration at 30 (APD30) and 90 (APD90) percent of repolarization was measured from optically mapped, Langendorff-perfused wild type (WT) and ΔKPQ mouse hearts. Hearts were perfused with sodium concentrations of 145 or 160 mM, in the absence or presence of an intercalated disc adhesion inhibitor (βadp1) inducing perinexal widening. Results: At baseline with 145 mM sodium, APD30 and APD90 were significantly greater in ΔKPQ than WT hearts. Surprisingly, increased sodium (160 mM), significantly decreased APD90 in WT but not ΔKPQ hearts, which is inconsistent with results from the drug-induced LQT3 guinea pig model. In contrast, 160mM sodium significantly decreased APD30 in both genotypes suggesting elevated sodium increases the transient outward potassium current (Ito). Interestingly, with 145 mM sodium, βadp1 treatment did not significantly change APD30 or APD90 in either genotype. However, increasing sodium from 145 to 160 mM with βadp1 significantly increased APD90 in ΔKPQ hearts but not WT. Conclusions: Synergistic APD prolongation was modest in a genetic LQT3 mouse when elevating sodium and widening the perinexus relative to drug-induced LQT3 in guinea pig. A significant difference in action potential morphology between mice and guinea pig is the over-expression of Ito in mice and its absence in guinea pig. Future studies will investigate whether transient outward potassium channels contribute to the effect of high sodium on APD shortening during early repolarization.
Abstract P3021: Blocking Grk2-induced Adiponectin Receptor 1 Serine <sup>205</sup> Phosphorylation As A Potential Target Against Post-ischemic Pathological Remodeling
Authors: Jianli Zhao
Journal: Circulation Research (2022)

Background: Despite significantly reduced acute MI mortality in recent years, ischemic HF continues to escalate. Therapeutic interventions effectively reversing pathologic remodeling are an urgent unmet medical need. We recently demonstrated that AdipoR1 phosphorylation by GRK2 contributes to maladaptive remodeling in the ischemic heart. The current study clarified the underlying mechanisms leading to AdipoR1 phosphorylative desensitization, and investigated whether blocking AdipoR1 phosphorylation may restore its protective signaling, reversing post-MI remodeling. Methods and Results: Specific site(s) and underlying molecular mechanisms responsible for AdipoR1 phosphorylative desensitization were investigated in vitro (neonatal and adult cardiomyocytes). The effects of AdipoR1 phosphorylation inhibition upon adiponectin (APN) post-MI remodeling and HF progression were investigated in vivo. Among 4 previously identified sites sensitive to GRK2 phosphorylation, alanine substitution of Ser 205 (AdipoR1 S205A ), but not other 3 sites, rescued GRK2-suppressed AdipoR1 functions, restoring APN-induced cell salvage kinase activation and reducing oxidative cell death. AdipoR1 phosphorylation promoted clathrin-dependent (not caveolae) endocytosis and lysosomal-mediated (not proteasome) degradation, reducing AdipoR1 protein level and suppressing AdipoR1-mediated cytoprotective action. GRK2-induced AdipoR1 endocytosis and degradation were blocked by AdipoR1 S205A overexpression. Moreover, AdipoR1 S205E (pseudo-phosphorylation) phenocopied GRK2 effects, promoted AdipoR1 endocytosis and degradation, and inhibited AdipoR1 biological function. Most importantly, AdipoR1 function was preserved during HF development in AdipoR1 S205A KI mice. APN administration 7 days after MI reversed post-MI remodeling and improved cardiac function. However, re-expressing hAdipoR1 WT in AdipoR1-KO mice failed to restore APN cardioprotection. Conclusion: Ser 205 is responsible for AdipoR1 phosphorylative desensitization in the failing heart. Blockade of AdipoR1 phosphorylation followed by pharmacologic APN administration is a novel therapy effective in reversing post-MI remodeling and mitigating HF progression.
Abstract P3051: Yap Regulates Serine Biosynthesis During Compensatory Cardiac Hypertrophy
Authors: Chengchen Hu, Junichi Sadoshima
Journal: Circulation Research (2022)

Introduction: In response to increased workload, cardiomyocytes increase in size, and the heart undergoes hypertrophy. The initial hypertrophy is a compensatory process that adds contractile units but reduces wall stress to help maintain heart function. Yes-associated protein (YAP), a major effector of the Hippo pathway, is transiently activated in response to acute pressure overload (PO). Cardiac-specific heterozygous downregulation of YAP inhibits hypertrophy but promotes heart failure, suggesting that endogenous YAP is salutary and mediates compensatory hypertrophy during the acute phase of PO. However, the mechanism by which YAP mediates compensatory hypertrophy is not well understood. We have shown previously that 3-phosphoglyceric acid and serine accumulate in the heart during acute PO in a YAP-dependent manner. The serine biosynthetic pathway provides precursors for the TCA cycle and antioxidant and purine biosynthesis. Hypothesis: YAP induces serine synthesis, thereby promoting compensatory cardiac hypertrophy in the presence of acute PO. Methods and Results: We evaluated the levels of intermediate enzymes in the serine synthesis pathway in YAP-overexpressing neonatal rat ventricular myocytes (NRVMs). Furthermore, we investigated whether YAP-induced cardiomyocyte hypertrophy is inhibited by siRNA targeting serine biosynthesis enzymes. Immunofluorescent staining of NRVMs with cardiac troponin T was conducted to evaluate cardiomyocyte size, which was assessed using ImageJ software. YAP upregulated protein levels of phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), phosphoserine phosphatase (PSPH), and serine hydroxymethyltransferase 1 (SHMT1) in NRVMs. siRNA-mediated downregulation of PHGDH, PSAT1, PSPH, or SHMT1 significantly inhibited YAP-induced cardiomyocytes hypertrophy. Conclusions: YAP upregulates the expression of enzymes in the serine biosynthesis pathway, thereby inducing hypertrophy in NRVMs. Metabolites of the serine biosynthesis pathway may play an important role in mediating YAP-induced compensatory cardiac hypertrophy.
Abstract P1087: P21-activated Kinase 1 Regulates Intrinsic Pacemaker Activity Through HCN4 Expression
Authors: Carlos H Pereira, Kathrin Banach
Journal: Circulation Research (2022)

Introduction: Cardiac pacemaker activity generated in the sinoatrial node (SAN) depends on a coupled clock mechanism that consists of a calcium (Ca-) and a voltage clock (V m -clock). Attenuation of either clock results in bradycardia which increases the risk for atrial fibrillation (AF). We have previously demonstrated that p21-activated kinase 1 (Pak1) is a negative regulator of NADPH oxidase 2 dependent production of reactive oxygen species (ROS). Here we hypothesized that attenuated Pak1 activity increases the susceptibility for AF by attenuating SAN function. Methods: In wild type (WT) and Pak1 knock-out (Pak1 -/- ) mice (FVBN), ECGs and atrial electrograms were recorded in vivo and in isolated Langendorff (LD)-perfused hearts. Results: Pak1 -/- compared to WT mice exhibited an attenuated intrinsic HR in vivo after autonomic blockage with atropine (1 mg/kg) and propranolol (1 mg/kg) (WT: 399 ± 8.05 bpm, n=16; Pak1 -/- : 365 ± 9.6 bpm, n=13, p&lt;0.05) and in the isolated heart (WT: 343 ± 8.5 bpm, n=24; Pak1 -/- : 280 ± 6.03 bpm, n=28, p&lt;0.01), suggesting attenuated SAN impulse generation. Block of the Ca-clock (cyclopiazonic acid (CPA): 5 μM) did not eliminate the difference in HR. Block of the V m -clock with the hyperpolarization activated cyclic nucleotide gated channel (HCN4) blocker ivabradine (IVA: 3 μM) however, had an attenuated effect on HR in Pak1 -/- (WT IVA : -45 ± 2.5 %, n=6; Pak1 -/- IVA : -22 ± 3.2 %, n=7, p&lt;0.001) and eliminated the difference in SAN frequency (WT IVA : 186 ± 17 bpm, n=6; Pak1 -/- IVA : 234 ± 15 bpm, n=7) supporting a decreased V m -clock function. Attenuated HCN4 expression in Pak1 -/- could be recovered by suppression of Histone deacetylases class II activity (LMK235: 5 mg/kg/day, 3 days); WT LMK : 322 ± 9.4 bpm, n = 5; Pak1 -/- LMK 314 ± 3.4 bpm, n= 5;) as well as by scavenging of ROS (TEMPOL supplemented drinking water, 2 mmol/L, 3 days; WT Tem : 332 ± 12.7 bpm, n = 5; Pak1 -/- Tem : 318 ± 22 bpm, n= 5). Both treatments, restored the contribution of V m -clock to pacemaker activity in Pak1 -/- animals (WT LMK : -38 ± 8.3%, n = 5; Pak1 -/- LMK : -38 ± 1.2%, n= 4; WT Tem : -46 ± 3.7 %, n = 5; Pak1 -/- Tem : -41 ± 2.5 %, n= 5) and attenuated AF inducibility. Conclusion: In both sexes attenuated Pak1 signaling results in SAN bradycardia by ROS/HDAC dependent suppression of HCN4 expression.
Abstract P2012: GRK2-Induced Cardiomyocyte AdipoR1 Phosphorylation Blocks Adipocytes-Derived Exosomes Cardioprotection Against Ischemic Heart Failure
Authors: Zhen Zhang, Di Zhu, Zhijun Meng, Jianli Zhao, Fujie Zhao, Peng Yao, jumpei tsukuda, Demin Liu, Lu Gan, Wayne Bond Lau, Dina Xie, Bernard L Lopez, Theodore Christopher, Erhe Gao, Walter Koch, Xinliang Ma, Yajing Wang
Journal: Circulation Research (2022)

Background: Despite significant reduction in acute MI death, ischemic heart failure (IHF) and resultant death continually escalate with incompletely understood mechanism. We recently reported that adipocyte-derived exosomes (ADp-Exo) protect heart from acute MI/R injury. However, it remains unknown whether and how cardiomyocytes (CM) response to ADp-Exo is altered during the chronic phase of MI, negatively impacting IHF development. Methods and Results: Intramyocardial injection of ADp-Exo (isolated from epididymal fat pad) immediately after MI (90 min MI/4 weeks reperfusion) significantly attenuated post-MI remodeling. However, the protective effects were completely lost when ADp-Exo were administered 1 week after MI. To identify the molecular mechanisms responsible for ADp-Exo cardioprotection and its alteration during chronic MI, a series of in vitro experiments were performed. Adiponectin (APN), a potent cardioprotective adipokine, was detected on the surface of ADp-Exo (Exo-flow kit). Treatment of CM with ADp-Exo activated multiple cell salvage kinases (e.g., ACC, ERK and AMPK). These effects were lost in APN neutralization antibody pre-incubated ADp-Exo or ADp-Exo from APNKO mice, suggesting Exo surface APN may mediate ADp-Exo cardioprotection. Moreover, ADp-Exo cell salvage kinase activation effect was absent in CM from AdipoR1KO mice or GRK2 transfected CM, suggesting GRK2-induced AdipoR1 phosphorylation at Ser 205 (as we demonstrated in Circulation, 2015 and Circ Res, 2022) is likely responsible for incapability of ADp-Exo protection during post-MI remodeling. To obtain direct evidence supporting this novel hypothesis, AdipoR1 S205A or AdipoR1 S205E (pseudo-phosphorylation) mice were generated. ADp-Exo cardioprotection was restored in AdipoR1 S205A mice, even when they were administered 1 week after MI. In contrast, ADp-Exo cardioprotection was lost in AdipoR1 S205E mice, even when they were administered immediately after MI. Conclusions: We demonstrate for the first time that, APN located on the surface of ADp-Exo acts as the critical executor of ADp-CM communication, mediating ADp-Exo cardioprotection. GRK2-induced CM AdipoR1 phosphorylation blocks ADp-Exo protective action, contributing to IHF progression.
Abstract P2095: Role Of Intraplaque Lipids In Atherosclerotic Plaque Vulnerability
Authors: Pricila K Moly, Nezam Haider, Mohamed Zayed, Joshua Black, Bahaa Succar, Emile Saad, Wei Zhou
Journal: Circulation Research (2022)

Background: Hyperlipidemia plays a pivotal role in the pathogenesis of diabetes, atherosclerosis, and cardiovascular diseases. Specific lipids of atherosclerotic plaques are potentially one of the local factors which render them susceptible to rupture. Their underlying unresolved inflammation and oxidative stress contribute to the transition from stable to unstable plaques. Therefore, we aimed to identify, characterize, and compare the intraplaque lipids composition among diabetic and non-diabetic patients and to ascertain their role in inflammation, and atherosclerotic plaque destabilization and rupture. Methods: Approved by the IRB, University of Arizona, Tucson Lipids were analyzed by liquid chromatography-mass spectrometry (LC-MS) from 40 surgically removed endarterectomy specimens that include Asymptomatic &amp; Non-diabetic (n=13), Symptomatic &amp; Non-diabetic (n=17), Asymptomatic &amp; Diabetic (n=5) iv. Symptomatic &amp; Diabetic (n=5) patients. Seventy nine lipid species from the main lipid classes phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylinositol (PI), cholesteryl ester (CE) phosphatidylglycerol (PG), sphingomyelin (SM), and ceramide (Cer) were included in this lipidomic profiling. Results: LC-MS data analysis identified a significant difference (p&lt;0.05) in 2 individual lipid species – a long chain polyunsaturated PC(40:7) and SM(18:1) between diabetic and non-diabetic (Table:1). A total of 23 lipid species were significantly (p&lt;0.05 to p&lt;0.005) differentially present between symptomatic and asymptomatic samples. Symptomatic diabetic and nondiabetic samples showed a significant (p&lt;0.05 to p&lt;0.005) difference in 13 lipids belonging to PC, SM and PE. Our studies also showed a higher peroxidation of intraplaque lipid from diabetic patients compared to non-diabetics, and a significant increase in reactive oxygen species (ROS) production in human coronary artery smooth muscle cells treated with lipids from diabetic plaques. Conclusions: This exploratory analysis showed distinct patterns of intraplaque lipid composition. Identification of these high-risk plaque lipid biomarkers will help to delineate the cellular and molecular mechanism responsible for stable to vulnerable plaques transition.
Abstract P3078: Stress-induced Early Recruitment Of Neutrophils To The Infarcted Hearts Influence Cardiac Outcomes.
Authors: Albert Dahdah, Ki H Park, Gopalkrishna Sreejit, Robert Jaggers, Jillian Johnson, Prabhakara R Nagareddy
Journal: Circulation Research (2022)

Myocardial infarction (MI)-induced heart failure is one of the leading causes of death in the modern world. This is in part due to abnormal cardiac remodeling, instigated by a large influx of neutrophils immediately following MI. These activated neutrophils in the heart release a plethora of proteolytic enzymes and exacerbate tissue injury leading to cardiac failure and death. The role of neutrophils during MI is complex with the intensity and duration of their residency dictating the ensuing remodeling process. We have previously shown that the recruitment of neutrophils to heart post-MI is mirrored by an increased proliferation of progenitors (granulopoiesis) in the bone marrow (BM). However, the increase in the number of neutrophils at the infarct begins much earlier (&lt; 6 hours post MI) than the peak granulopoiesis (24 hours post-MI) in the BM. These finding suggest that sources other than granulopoiesis may contribute heavily to the initial neutrophil burden of the heart. One such source is the marginated pool. In the circulation, the marginated pool of neutrophils represents the same size as that of the circulating pool. We hypothesize that “ demargination of neutrophils from the vascular wall contribute to the neutrophil burden of the heart particularly during the early hours after MI ”. To test this hypothesis, we created a mouse model of MI by permanent ligation of the left anterior descending coronary artery and studied the impact of early recruitment of neutrophil to ischemic heart. We found that the initial wave of neutrophils recruited to the ischemic heart were exclusively sourced from the vasculature and not granulopoiesis in the BM/ Spleen. The neutrophils that were recruited to the heart exhibit distinct hallmarks of demargination including decreased F-actin, CD62L and increased Adam17 expression. This early recruitment of neutrophils was orchestrated by catecholamine stress as strategies aimed at inhibition of catecholamine biosynthesis or blockade of β adrenergic receptors (β-AR) significantly reduced neutrophil burden and improved cardiac function. Interestingly, this protective effect was lost when neutrophil recruitment was suppressed over a longer period. In conclusion we show that while short-term blockade of β-AR signaling suppresses the early neutrophil swarming, suppression beyond the reparative phase (&gt; 3 days post-MI) adversely impact the cardiac function. Together these data suggest that catecholamine stress induced-demargination constitute the major source of neutrophils during the early hours of MI. Understanding the precise signaling mechanisms that drive demargination and optimizing the right dose/duration of a specific β-AR blocker may help suppress the initial onslaught of neutrophils without compromising their overall beneficial function during the reparative phase of inflammation.
Abstract P2045: Transcriptome Versus Proteomic Discrepancy Is Associated With Structural-functional Dys-synchrony In Reductive Stress Myocardium
Authors: Sini Sunny, Cynthia L David, Krishna Parsawar, Steven pogwizd, Rajasekaran N Namakkal-Soorappan
Journal: Circulation Research (2022)

Background: A real-time action of Nrf2 in response to a stress is vital to preserve the redox homeostasis, but its activation under unstressed settings tilt the redox balance towards the reductive arm, leading to reductive stress (RS). In this study, we identified that &gt;50% mismatch between mRNA and protein levels in RS myocardium undergoing structural/functional dys-synchrony. Methods: NGS-RNA Seq (for RNA), Tandem Mass Tagging (TMT) Mass spectrometry (for proteins) and speckle tracking strain echocardiography (STE) using Vevo2100 system was performed in the cardiac-specific constitutively active Nrf2 transgenic (CaNrf2-TG/TG) and non-transgenic (NTG) mice (n=4/group) at ~6-7 months of age. Results: Comparison of NGS and TMT data in TG vs. NTG hearts showed surprising results. Out of 104 commonly found gene products in NGS and proteins at a FC≥1.5, the levels of 50 proteins are not consistent with their RNA expression. The proteins that are steadily expressed according to their respective mRNA levels are classified as “transcription-sync proteins (T-SP)” and the ones that do not match are termed as “transcription-nonsync proteins. While changes in Nrf2-driven antioxidant genes ( Nqo1, Gsr, Gsta1-4, and Gstm1 ) were grouped under “T-SP”, other transcripts including Atp5pb, Ces1d, Cmbl, Cox7a1, Cpt1b, Fah and Gstk1 did not quantitatively match with their translated products in TG hearts. Further, STE demonstrated an impaired wall motion (diastolic and systolic velocity), increased fractional shortening (20% vs 50%; p&lt;0.0001), decreased global longitudinal strain (-10% vs -25%, p&lt;0.0002), increased IVRT (6.46 vs 13.8 ms; p&lt;0.0001) and IVCT (8.06 vs 12.5 ms; p&lt;0.0005) in TG vs. NTG mice. Changes in the systolic and diastolic functions with structural abnormalities demonstrate cardiac dys-synchronicity in TG hearts with chronic RS exhibiting impaired transcriptome and proteome profiles. Conclusions: Our comparative analysis of RNA and protein in RS hearts demonstrated that 50% of the proteins do not match with the quantitative changes of their transcripts. We highlight that the RS could be a novel mechanism for disproportionate transcription vs translation, which leads to structural and functional dys-synchrony in the TG hearts.